Motor control center subunit having moveable line contacts and method of manufacture
A system and method for connecting supply power to motor control components includes use of a motor control center subunit with moveable supply power contacts. After a motor control center subunit is secured into a motor control center compartment, the supply power contacts may be advanced to engage supply power buses. For disconnection, the supply power contacts may be retracted and isolated from the buses before physical removal of the subunit.
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The present application is a continuation of, and claims priority to, U.S. non-provisional application Ser. No. 12/708,873, filed Feb. 19, 2010, which claims priority to U.S. non-provisional application Ser. No. 11/625,088, filed Jan. 19, 2007, now U.S. Pat. No. 7,688,572, which claims priority to U.S. provisional application Ser. No. 60/833,380, filed Jul. 26, 2006, the disclosures of which are incorporated herein by reference.
BACKGROUND OF THE INVENTIONThe present invention relates generally to a system and method for motor control, and more particularly, to a subunit for a motor control center which connects motor control components to supply power, and a method of manufacture thereof. The system and method described herein provide for connection of the supply power to the motor control components after full installation of the motor control center subunit into the motor control center.
A motor control center is a multi-compartment steel enclosure with a bus system to distribute electrical power, on a common bus system, to a plurality of individual motor control units mountable within the compartments. The individual motor control units are commonly referred to as “buckets” and are typically constructed to be removable, pull-out units that have or are installed behind individual sealed doors on the motor control center enclosure. These buckets may contain various motor control and motor protection components such as motor controllers, starters, contactor assemblies, overload relays, circuit breakers, motor circuit protectors, various disconnects, and similar devices for operating high voltage motors. The buckets connect to the supply power lines of the motor control center and conduct supply power to the line side of the motor control devices, for operation of motors. Motor control centers are most often used in factories and industrial facilities which utilize high power electrical motors, pumps, and other loads.
Typically, when installing or removing motor control center buckets, the power supply lines are connected or interrupted. To remove such a bucket, a deadfront door of the bucket or of the motor control center is opened and an operator manually pulls on the bucket to separate the primary disconnects, or “stabs,” from the bus system, thereby disconnecting power supply. Installation of a bucket is accomplished in a similar manner, wherein the operator manually pushes the bucket into a compartment of the motor control center to engage the bucket stabs with the bus system, and thus connect the system to supply power. The line connections or stabs may be difficult to maneuver manually when an operator is supporting the entire bucket or when the stabs are not visible.
Attempts have been made to improve upon the manual installation and disconnection of motor control center buckets and supply power connections from live supply power lines, risers, and/or a vertical bus of a motor control center. Other systems have employed pivotable handles inside the buckets to pivot line connectors to and from supply lines. However, many of these systems require that the bucket or compartment door be open to manipulate the handles and line stabs.
It would therefore be desirable to design a motor control center bucket assembly that overcomes the aforementioned drawbacks. Thus, it would be desirable to provide for remote connection or disconnection of the line stabs of a bucket to the power supply lines or bus of a motor control center from a distance. In the event of an arc or arc flash, any heated gas, flame, and/or the arc itself should preferably be contained behind the bucket compartment door or “deadfront.”
BRIEF DESCRIPTION OF THE INVENTIONThe present invention provides a system and method for installing a motor control center subunit or bucket into a motor control center and electrically connecting motor control components of the bucket to a power supply. The system and method utilize moveable line stabs to engage the power supply (such as a series of bus bars) after the bucket has been secured in the motor control center, in order to contain potential arc flashes.
Therefore, in accordance with one aspect of the present invention, a control module for a motor control center is provided. The control module includes a housing having a plurality of conductive contacts therein. The housing has a front panel and is designed to seat in a motor control center whereupon the front panel forms a front face of the motor control center. The control module also includes an engagement mechanism which is attached to the housing and is in operable association with the plurality of conductive contacts. The engagement mechanism moves the plurality of conductive contacts between a retracted position and an extended position while the control module housing is seated in the motor control center and the front panel is in a closed position.
In accordance with another aspect of the invention, a method of manufacturing a control module for a motor control center is provided. The method includes assembling a control module housing to have at least a front panel and to seat in a motor control center, disposing a moveable guide within the control module housing to guide motion of at least one supply contact from a first position to a second position, attaching the at least one supply contact to the moveable guide, and providing for advancement of the at least one supply contact and the moveable guide when the front panel of the control module housing is secured against the motor control center compartment.
According to a further aspect of the invention, a motor control center subunit includes a subunit housing, an actuating mechanism, and an isolator assembly. The subunit housing is designed to be installed in a motor control center. The actuating mechanism is disposed within the subunit housing and is constructed to move a plurality of line connectors between a retracted position and an extended position. The isolator assembly is configured to electrically shield the plurality of line connectors prior to engagement of the plurality of line connectors with a line power.
In accordance with another aspect of the invention, a motor control center is provided that includes a frame and at least one control unit. The frame encloses a supply power bus and has at least one compartment. The at least one control unit is configured for substantially sealed installation in the at least one compartment, and includes at least one supply power contact, a drive configured to move the at least one supply power contact for engagement and disengagement with the supply power bus, and a drive actuator designed to actuate the drive from without the control unit when the control unit is installed in the at least one compartment.
Various other features and advantages of the present invention will be made apparent from the following detailed description and the drawings.
The drawings illustrate one preferred embodiment presently contemplated for carrying out the invention.
In the drawings:
The following description makes reference to supply power, supply power lines, motor power, load power, line power, and the like. It is appreciated that such terms may refer to a variety of both common and uniquely conditioned voltage and current characteristics, including but not limited to, three phase AC power, single phase AC power, DC power, multiple DC power lines, or any combination thereof. Such power characteristics will be generally referred to as being provided on a bus, supply line, or riser of a motor control center. However, it is appreciated that the present invention may find applicability in other power connectivity configurations, adapted or apart from motor control centers. An example of supply power commonly used in motor control centers is 480V three-phase AC power distributed over three separate supply buses.
Referring to
Referring now to
When slide 32 of line contact actuator 31 is moved aside, an opening 36 is exposed. Opening 36 preferably has a unique configuration to accept a specialized crank 34 (as shown in
Bucket 16 also includes a number of conductive line contacts or stabs 44, 46, 48, 50. Control power contact 44 is preferably fixedly attached to the rear of bucket 16, whereas supply power stabs 46, 48, 50 are moveable with respect to bucket 16. However, it is appreciated that control power contact 44 may also be moveable in a similar manner to line power stabs 46, 48, 50. Control power contact 44 is of a suitable construction to conduct a control power (typically a few volts) to motor control components (not shown) disposed within bucket 16. In embodiments where control power contact 44 is permanently positioned at the rear of bucket 16, control power contact 44 will engage a control power supply line or bus 47 upon installation of bucket 16 into a motor control center.
Supply power stabs 46, 48, 50, on the other hand, do not engage supply power lines or buses when bucket 16 is installed into a motor control center. Rather, stabs 46, 48, 50 are initially in retracted position 42, as shown in
Referring now to
Also shown in
Likewise, for removal of bucket 16, circuit breaker 28 (
Referring now to
Referring now to
In other embodiments, it may be desirable to use more automated actuation of the stabs of a motor control center bucket. Accordingly,
Accordingly, one embodiment of the present invention includes a control module for a motor control center. The control module includes a housing having a plurality of conductive contacts therein and a front panel, the control module being designed to seat in a motor control center such that the front panel forms a front face of the motor control center. The control module also includes an engagement mechanism which is attached to the housing and is in operable association with the plurality of conductive contacts. The engagement mechanism moves the plurality of conductive contacts between a retracted position and an extended position while the control module housing is seated in the motor control center and the front panel is in a closed position.
Another embodiment of present invention includes a method for manufacturing a control module for a motor control center in which a control module housing is assembled to have at least a front panel and to seat in a motor control center, a moveable guide is disposed within the control module housing to guide motion of at least one supply contact from a first position to a second position, and the at least one supply contact is attached to the moveable guide. The method also includes providing for advancement of the at least one supply contact and the moveable guide when the front panel of the control module housing is secured against the motor control center compartment.
In another embodiment of the present invention, a motor control center subunit includes a subunit housing, an actuating mechanism, and an isolator assembly. The subunit housing is designed to be installed in a motor control center. The actuating mechanism is disposed within the subunit housing and is constructed to move a plurality of line connectors between a retracted position and an extended position. The isolator assembly is configured to electrically shield the plurality of line connectors prior to engagement of the plurality of line connectors with a line power.
In accordance with another embodiment of the present invention, a motor control center is provided. The motor control center includes a frame enclosing a supply power bus and having at least one compartment, and at least one control unit. The at least one control unit is configured for substantially sealed installation in the at least one compartment, and includes at least one supply power contact, a drive configured to move the at least one supply power contact for engagement and disengagement with the supply power bus, and a drive actuator designed to actuate the drive from without the control unit when the control unit is installed in the at least one compartment.
The present invention has been described in terms of the preferred embodiment, and it is recognized that equivalents, alternatives, and modifications, aside from those expressly stated, are possible and within the scope of the appending claims.
Claims
1. A control module for installation in and removable from a motor control center having a power supply, the control module comprising:
- a control module housing having a front panel;
- an actuating mechanism positioned within the control module housing to control movement of a plurality of contacts between a disengaged position and an engaged position; and
- an isolator assembly mounted to the control module housing to selectively electrically isolate the plurality of contacts from the power supply.
2. The control module for a motor control center of claim 1 wherein the isolator assembly comprises at least one angled portion that engages the plurality of contacts during movement of the plurality of contacts.
3. The control module for a motor control center of claim 1 wherein the isolator assembly comprises an insulating material.
4. The control module for a motor control center of claim 1 wherein the isolator assembly comprises a plurality of shutters constructed to translate horizontally between an open position and a closed position to selectively electrically isolate the plurality of contacts from the power supply.
5. The control module for a motor control center of claim 1 wherein the isolator assembly comprises a plurality of shutters moveable between an open position and a closed position; and
- wherein a first shielding portion of the isolator assembly overlaps a second shielding portion of the isolator assembly in the closed position.
6. The control module for a motor control center of claim 5 wherein the first and second shielding portions are biased toward one another such that the isolator assembly automatically closes upon movement of the plurality of contacts from the engaged position to the disengaged position.
7. The control module for a motor control center of claim 1 further comprising a shutter indicating mechanism coupled to the isolator assembly, the shutter indicating mechanism configured to display whether the isolator assembly is in an open position or a closed position.
8. The control module for a motor control center of claim 1 further comprising a crank coupleable to the actuating mechanism to control actuation thereof.
9. The control module for a motor control center of claim 1 further comprising a slide having an opening therein to receive the crank, wherein a surface of the slide engages the front panel to lock the front panel in a closed position.
10. The control module for a motor control center of claim 1 further comprising a control power contact accessible from outside the control module housing and configured to engage a control power supply and conduct a control power to control components within the control module housing.
11. A method of manufacturing a control module for a motor control center, the method comprising:
- positioning at least one contact within a control module housing;
- coupling an actuating mechanism to the at least one contact to control movement thereof between a first position wherein the at least one contact is retracted within the control module housing and a second position wherein the at least one contact extends outside the control module housing; and
- attaching an isolator assembly to the control module housing, the isolator assembly comprising at least one shutter.
12. The method of claim 11 further comprising biasing the at least one shutter in a closed position wherein a first portion of the at least one shutter overlaps a second portion of the at least one shutter.
13. The method of claim 12 further comprising aligning the at least one contact with the isolator assembly such that the at least one contact impinges upon the first and second portions of the at least one shutter during movement of the at least one contact from the first position to the second position.
14. The method of claim 11 further comprising:
- coupling a shutter position display to the control module housing; and
- coupling a shutter indicating mechanism between the shutter position display and the isolator assembly.
15. The method of claim 11 further comprising aligning the at least one contact with the isolator assembly such that the at least one contact extends through an opening in the at least one shutter.
16. A motor control center comprising:
- a mounting frame having a plurality of compartments;
- a power bus provided within the mounting frame;
- a control module sized to seat within one of the plurality of compartments of the mounting frame, the control module comprising: a housing; a plurality of contacts positioned within the housing and coupled to an actuating mechanism that is moveable between a first position and a second position, wherein the plurality of contacts are retracted within the housing in the first position and engage the power bus in the second position; and an isolator assembly mounted to the housing to electrically isolate the plurality of contacts from the power bus when the plurality of contacts are in the first position.
17. The motor control center of claim 16 wherein the isolator assembly comprises a first shielding portion and a second shielding portion.
18. The motor control center of claim 17 wherein the first and second shielding portions are biased toward one another in a closed position.
19. The motor control center of claim 17 wherein the first and second shielding portions comprise angled surfaces.
20. The motor control center of claim 17 wherein the first shielding portion overlaps the second shielding portion.
21. The motor control center of claim 16 wherein the plurality of contacts are positioned within the housing with respect to the isolator assembly such that a respective contact of the plurality of contacts impinges upon the isolator assembly during movement of the actuating mechanism from the first position to the second position.
22. The motor control center of claim 19 wherein a respective contact of the plurality of contacts impinges upon the first and second shielding portions of the isolator assembly during movement of the actuating mechanism from the first position to the second position.
23. The motor control center of claim 16 wherein the control module further comprises a control power contact accessible from outside the housing and configured to engage a control power supply of the motor control center and conduct a control power to control components within the housing.
24. The motor control center of claim 16 further comprising a rotatable crank coupled to the actuating mechanism to control movement thereof.
25. The motor control center of claim 16 further comprising:
- a shutter indicating mechanism coupled between the isolator assembly and an indicator visible from outside a front surface of the housing; and
- wherein the indicator displays whether the isolator assembly is in one of a closed position and an open position.
26. A control module for a motor control center comprising:
- a control module housing having a front panel;
- a shutter comprising a two-piece assembly positioned within the control module housing to electrically isolate a plurality of contacts; and
- an actuating mechanism positioned within the control module housing to control movement of the plurality of contacts between a disengaged position wherein the plurality of contacts are positioned behind the shutter, and an engaged position wherein the plurality of contacts extend through the shutter.
27. The control module of claim 26 further comprising an indicator mechanism coupled to the front panel of the control module housing and configured to display whether the shutters are open or closed.
28. The control module of claim 26 wherein each of the plurality of contacts extends through an opening in the shutter to engage the external power supply.
29. A control module for a motor control center comprising:
- a housing sized to seat within one of a plurality of compartments of the motor control center;
- at least one contact positioned within the housing and moveable between a first position and a second position, wherein the at least one contact is retracted within the housing in the first position and extends outside the housing to engage a power bus in the second position; and
- a shutter assembly moveable between an open position and a closed position;
- wherein a first portion of the shutter assembly meets a second portion of the shutter assembly in the closed position to electrically isolate the at least one contact from the power bus; and
- wherein the first portion separates from the second portion to permit the at least one contact to pass through the shutter assembly in the open position.
30. The control module of claim 29 wherein the first portion of the shutter assembly overlaps the second portion of the shutter assembly in the closed position.
31. The control module of claim 1 wherein the isolator assembly is positioned with respect to the plurality of contacts such that the plurality of contacts extends through the isolator assembly during movement of the plurality of contacts from the disengaged position to the engaged position.
32. The control module of claim 1 wherein the isolator assembly is positioned with respect to the plurality of contacts such that the plurality of contacts impinges upon the isolator assembly during movement of the plurality of contacts from the disengaged position to the engaged position.
33. The method of claim 11 further comprising aligning the at least one contact with the isolator assembly such that the at least one contact is extendable through an opening in the isolator assembly during movement of the at least one contact from the first position to the second position.
34. The method of claim 11 further comprising aligning the at least one contact with the isolator assembly such that the at least one contact impinges upon the isolator assembly during movement of the at least one contact from the first position to the second position.
35. The motor control center of claim 16 wherein the isolator assembly opens to expose the plurality of contacts to the power bus during movement of the plurality of contacts from the first position and the second position.
36. A motor control center comprising:
- a frame that defines a plurality of compartments and encloses a power bus,
- a control unit configured to be installed into and removed from one of the compartments of the frame, the control unit comprising:
- a control unit housing;
- an actuating mechanism disposed within the control unit housing and configured to selectively move, independent from movement of the control unit housing, a plurality of stabs between a disengaged position and an engaged position; and
- a shutter assembly mounted to the control unit housing and configured to be movable between an open position to permit the stabs to engage the power bus when the plurality of stabs are in the engaged position and a closed position to electrically isolate the plurality of stabs from the power bus when the plurality of stabs are in the disengaged position.
37. The motor control center of claim 36, further comprising:
- a shutter indicator configured to display whether the shutter assembly is in the open or closed position.
38. The motor control center of claim 37 wherein the shutter indicator is positioned on a front surface of the control unit housing.
39. The motor control center of claim 37 further comprising a shutter indicating mechanism coupled between the shutter indicator and the shutter assembly.
40. A control unit for a motor control center having a frame that defines a plurality of compartments, the control unit comprising:
- a control unit housing configured to be installed into and removed from one of the compartments of the frame;
- an actuating mechanism disposed within the control unit housing and configured to selectively move, independent from movement of the control unit housing, a plurality of stabs between a disengaged position and an engaged position; and
- a shutter assembly mounted to the control unit housing and configured to be movable between an open position and a closed position to electrically isolate the plurality of stabs from a power bus when the plurality of stabs are in the disengaged position.
41. The control unit of claim 40, further comprising:
- a shutter indicator configured to display whether the shutter assembly is in the open or closed position.
42. The control unit of claim 41 wherein the shutter indicator is positioned on a front surface of the control unit housing.
43. The control unit of claim 40 wherein the plurality of stabs extend through openings in the shutter assembly to engage the power bus.
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Type: Grant
Filed: Nov 5, 2012
Date of Patent: Jun 14, 2016
Patent Publication Number: 20130088812
Assignee: Eaton Corporation (Cleveland, OH)
Inventors: Edgar Yee (Chapel Hill, NC), Robert A. Morris (Fayetteville, NC), Scott E. McPherren (Chico, CA), Neal Edward Rowe (Cary, NC)
Primary Examiner: Jenny L Wagner
Assistant Examiner: Michael E Moats, Jr.
Application Number: 13/668,501
International Classification: H02B 11/173 (20060101); H02B 1/36 (20060101); H02B 11/24 (20060101);